Gauge tube



- 1934- J. B. FOURNIER 1,984,734

GAUGE TUBE Filed Sept. 22, 1950 FIG.4 FIG.4 FIG.5

Patented Dec. 18, 1934 UNIT?- sTA ,GAUGE TUBE Joseph Barbe Fournier, Sis-Mande, France In France October 4,1929

L AnPfiction Septeniber 22, 1930, SerialNo. 483,697

This invention relates to the manufacture nt gangs tubes used for the measuremnt of pressure, or for instruments :suchas 1ong-disttince5gaus or .thermometers; ..Tubes of .this character are 5 usua1iy ellipticaland in the finished product they are usually torus-shaped.

In practice they are generally subjected to considerable pressure and theefiect .01 this pressure reacts chiefly upon theplugs whieh close the ends of the torus and on the generatrices determined by the two extremitiesof the small axis oithe elliptical cylinder formedhy the tube beiore it is curved into torusnshape: These plugs which ci course are shaped in aceordance with the exterior or the interior of the tube are welded to the extremities with a compound, generaily tin, which will.melt at relatiVe1y 10W temperatures. The construction outlined is obviously unreliable for not only is the hardening of the metal altered by over heating, but thetin ofiers far less resistance to the pressure inside the tube than meta1s which malt at a much higher temperature, such as silver or copper. HoweVer, these latter metals areunsuitablfor the purpose in question as the temperature to which the two endsof the gauge tube would have to be subjected would have a. considerable effect on the piiabflity of the tube and consequently the sauge tube would notregister correctly since its needle is controlied by the tube. For this reason tin continues to be used, and although grooves are constructed where the p1ugscome into direct contact, nevertheless leaks always originate because of the partial Or total loosening of the plugs under the pressure inside the torus. Various attempts have benmade to eliminate such leaks While at the'same time sec1iring the proper piiabi1ity ofthe tube. Amongthet attempts it may be mentiond that the tube has been made with cyliridrical extremities; threaded upon either the inside or the outside, thereby allowing the tubet beclosed or corinected in any suitable manner With a smaller tube Which commuuicates in-turn with the area having the pres sure to be nieasured. Nevertheless, the above mentioned defects have not as yet been satisfac- It is an object of the present invention completely remove these defects by 3. construction whereby the endsof the tubes cau either'be closed or connected by meansof autogenous welding, si1ver, or tin withdut atfecting the,pliability of the gauge tube in the slightest degree.

The gauge tube according to the present in-' vention is made in one torus-shaped piece and extended into other tubes having a smaller diameter. These latter tubes have a length sufficient to permit the closing or the connecting welding o-f the tube suificientiy far from the gauge tube itself so that the heat requiredufor the we1d ing will have no effect upon thepliability of the tube, Accordingly; the tubes to be* closed may have as small a diameteras desired and since the force which tends to dislodge the plugs is proportional to the area of the surface of the plugs upon which the pressure is exerted, ail leaks from theplugs and all risks of leaks from the weldings connecting the tubes are avoided, especially in the case of long-distance measurements of pressures and 'temperature where the small tubes necessarily have a considerable length between the sauge itself and the area being measured.

In the figures, wherein similar reference characters refer.to like parts,

Figures 1 and 2 are diagrammatic representations et the cross sections 01 tubes,

Figures 3, 4 and 5 illustrace diflerent stages in the method of producing the tubes, and

Figures 6 and 7 show tubes bent into the form of a torus.

The tubes described below are generafly obtained from a metallic tube whichis usually cylindrical. First this tube is drawn out at an end so as to have one portion of the original diameter lengthened by a flexible tube a of small diameter. Inside the main portion of the tube an elongated body B is placed. This may be of any shape, but is preferably cylindrical and it is placed in such a way that one of its extremities touches the bottom 01 the tube where it joins the flexible tube ja of small diameter. body B Wili beirmed'themandrel:and it may consist of a metal rod, a bunch of:metal threads, etc. Upon thedrawing the-body of the solid mandre1 Bis represented by section fines, but the tube may have a liquid mandrel and be emptied of this liquid when it is the shape desired.

A tube is formed composed of three parts, the

cylindricai part having the same diameter as the original tube, the cy1indrical part 1 of small diameter and the eliiptical portion -A connecting the two preceding parts; Inside the latter is the bodyormandrelB. r 1 ,By drawing out the cylindrical part of the original diameter, a tube A? is obtained Which can be 01 as small diameter as desi'red. 7

In regard to the body or niandrel B ,introduced into the part A of the tube, this cannot as a ru1e be WithdraWtb but the presence of this body in the gauge tube is generally advantageous since the interior capa city of the tube is thereby lessened and the tube Wi1l curvebetter into the shape of a torus. 'Naturaily' the section of the body B is such that While iaCiiitating thes'hapingbf th tube, it does not block the tube completeiy and permits the sauge fluid to flow freely. If, however, the presence of the mandrel in the tube is undesirable, the 'metal mandrel can berepiaced' by a liquid body such as water or fine particles of solid matter such as sand. This may be done in the following manner.

The two extremities of the original cylindrica1 tube are lengthened into-two narrow tubes. One of these tubes is hermeticallsr sealed by. a wire or small rod. At the other extremity a quantity of water is introduced into that pore quired so as to facilitate the setting up. The tubes'may also be spirally rolled in one or sevtion of the tube which it is desired to lengthen. The tube is then closed. Several strokes are every stroke until the cylindrical part has obtained the elliptical shape desired; A'certainlength of the small rod closing one of the ext1em ities of the tube is then withdrawn so as-to avoid the elliptical tube becoming mis-shaped since liquid cannot be compressed. The tube is then given a torus shape; Then the two sniall tubes are uncovered, allowing the water,to flow awa and the gauge tube is completed. Sometimes the elliptial type of tube is: unsuitable, particularly when very great pressures are to be measured which may bend the tube out of shape or even burst thesame. The pressure at the inside of the tube acts upon the opposite concave surfaces A,B, CA,D, C and tends to transform the tube into a tube having circular sections. In order to avoid these results a hy+ perbolic gauge tube may be obtained, in.which case the two concave surfaces referred to above are replaced by two convex surfaces. The right section of such a tube is shaped like a hyperbole a, b, ca, b, c (see Fig. 2), in which the two arcs are joined by tWo cur'ves a, a c, c The two extremities of a tube thus obtained are prolonged in the manner as stated above with reference to the elliptical tubes, a hyperbolic gauge tube will be secured inone piece with its capillary prolongations at each eXtremity thereof.

Figure 3 illustrates a tube s'uitablefor certain uses. A part of the Cylindrical tube is prolonged into a flexible tube A of the requiredlength and terminates at its other extremity in acylindrical tube C of a diameter equalto that of the original tube or difierent therefrom, if desired. The tube in Figure 3 showsa Small diameter tube a made from the elliptical part A containing the mandrel B which will be the tube of the gauge instrument and the" small'ifiube A will constitute the transmission tube; while the cylindrical part having thelarger diameter C will be located in the position where measurements are to be taken. The connection of the elliptical tube A by means of the small tube A with the cylindricaLl reservoir C is suitable for the construction of long-distance thermometers of metal operating either b'the-expansion of mercury or by the tension of steam vapors. In such case the small diameter tube A will be the transmission tube from the place at which the temperature is being measured to the place where the temperature is being noted.

Mercury attacks allordinai*y metals "except steel. The outside of the gauge or the. thermometeric envelope in which mercury is tolbe placed so as to act as a thermometric agent must theref0re be entirely of steel without any soldering. 'Ihe thermometric envelope in such an instrument is composed of the gauge tube, et a flexible tube of the desired length according to the size of the instrumentand a small metal tube acting as a thermometric reservoir. Such a device as shown in Figure 3, can be usedas a thermometric envelope whether the thermometric agent is mercury or anyother fluid.

The gauge tubes obtained are rolled around suitable mandrels to be transformed into gauge tubes having the shape of a torus such as those shovvn in Figures 6 and "I. The .small end tubes 1'and p? can have upon the same gauge tube diameters and lengths which are unequal. They may also have the cylindrical parts 23 if reeral ,spiralsand the spirals may be helicoidal or hyperbolic, etc.

In the tubes-made according to the invention theblugs WhCh are always liable to leak are eliminated since the operation of blocking is performed at a distance from the gauge tube by placing very small quantity of soldering in one of thesmall tubes 27 or :0 thereby prolonging the:gaugetube itself which acts as an actuator for the.needle indicating the pressure. The force acting upon'tiie point where the small tube is soldered which closes'a mm. tube for example, and having therefore an area of sq. mm., is to the plugs of an elliptical tube having an area of 48 sq. mm;, which is the usual dimension for gauge tubes, as 2 is to 488, which means that the force acting 'upon the soldering closing the gauge tube in accordance with the invention is 244 times less than that acting upon the plugszof gauge tubes used at,the present time. In addition,the soldering in tubes made according to the present invention is located at a distancefrom the gauge tube itself, that is, from that part of the tube which is usually torusshaped and used as the actuator for the needle. With such a construction the pliability of the tube cannot be altered or afiected by the heat necessary for soldering. Water-tight conditions are thereforeobtained which were impossible to obtain before, and the stability and functioning of the tubes as constructed according to the present invention are largely improved when compared with the usual gauge tubes. Furthermore, any overheating of the tube must be avoided when the tube is fixed to the box. Consequently no soldering should be used which is liable to overheat the tube when this operation is performed. The tubema.y .be fixed in the box by using the bosses made in it .at the time. the tube is prolonged, and thesebosses may be threaded or prismatic.

It is understood that the construction described above is,merely a preferred form of the invention and isnot to be interpreted in, a limiting sense.

Iclaim:

; 1. .Manometric tube inwhich the torus shaped body.;of the tube,- serving to actuate a needle or -indicator element, is continued at each end by extensions integral with said torus and consisting of tubes having a capillary bore, the length of which vis such that the closure or junction seams are situated at a sufficient distance from the torus so that the heat produced by the welding, soldering or seaming cannot affect the elasticity of the active portion of the tube.

2. A one piece manometric assembly including a manometric tube having a torus shaped body serving to actuate an indicator element, said body being continuous at each end with integral extensions in the form of tubes having a capillary bore, and a hollow chamber integral and continuous with one of said tubes, said chamber having a larger section than the tube to which it is connected and being adapted to receive a fiuid whose pressure is to be measured.

; x v JOSEPH BARBE FOURNIER. 

